Quick Facts
| CAS Number | 443-48-1 |
|---|---|
| Molecular Formula | C6H9N3O3 |
| Molecular Weight | 171.156 |
| Pharmacopoeia | BP，USP,EP |
| Packaging | 25 KG/DRUM |
Product Story
Metronidazole was first synthesized in the 1950s by scientists at Rhone-Poulenc (now Sanofi) in France, emerging from their program to develop nitroimidazole derivatives from the natural antibiotic azomycin. The key breakthrough came in 1959 when researcher Cosar serendipitously observed that metronidazole cured a patient's trichomoniasis while being administered for bacterial gingivitis. This accidental discovery redirected the compound from an antibacterial to a potent systemic antiprotozoal agent, and it was launched in 1960 under the brand name Flagyl.
Metronidazole's mechanism of action is unique among antimicrobials. The drug acts as a prodrug — its nitro group is enzymatically reduced by ferredoxin or similar electron-transport proteins present only in anaerobic bacteria and protozoa. The reduced intermediates form covalent adducts with DNA, causing helical destabilization, strand breakage, and cell death. Because the reductive activation requires a low redox potential, metronidazole selectively targets obligate anaerobes while leaving aerobic human cells unaffected.
Metronidazole's key advantage is its narrow-spectrum precision: it kills anaerobic pathogens with minimal disruption to the aerobic microbiota. Unlike broad-spectrum beta-lactams, it does not promote C. difficile overgrowth — in fact, it is a first-line treatment for C. difficile colitis. Small, uncharged, and lipophilic, metronidazole achieves excellent tissue penetration including the blood-brain barrier, making it effective for anaerobic brain abscesses. It is on the WHO Model List of Essential Medicines and remains, after nearly 70 years, the standard of care for trichomoniasis, bacterial vaginosis, amebiasis, and giardiasis.
As of mid-2026, the global metronidazole API market is driven by sustained demand in both human and veterinary sectors, with China and India as dominant manufacturing hubs. Metronidazole is also extensively used in poultry and swine production for anaerobic enteritis and histomoniasis (blackhead disease). The dual human-veterinary demand stabilizes the market, though environmental regulatory scrutiny on nitroimidazole residues in food-producing animals is intensifying, shifting demand toward higher-purity GMP-grade material with well-characterized impurity profiles.
Quality Specifications
| Purity (HPLC) | ≥ 99.0% (anhydrous basis), per BP/USP/EP monograph |
|---|---|
| Related Substances | 2-Methyl-5-nitroimidazole (starting material) ≤ 0.1%; any individual unspecified impurity ≤ 0.1%; total impurities ≤ 0.5% (EP) |
| Residual Solvents | Compliant with ICH Q3C; formic acid ≤ 5,000 ppm |
| Heavy Metals | ≤ 20 ppm |
| GMP Status | Manufactured under ICH Q7 GMP conditions |
| Key Tests | Melting point 159-163 °C; loss on drying ≤ 0.5%; appearance: white to pale yellow crystalline powder |
Pharmaceutical Applications
- Anaerobic bacterial infections: Potent activity against Bacteroides fragilis, Clostridium species, and anaerobic cocci. Penetrates abscesses and blood-brain barrier effectively.
- Bacterial vaginosis: Oral metronidazole 500 mg BID for 7 days. First-line CDC-recommended treatment for BV with cure rates exceeding 90%.
- Trichomoniasis: Single 2 g oral dose for Trichomonas vaginalis. Partner treatment recommended to prevent reinfection.
- Amebiasis and giardiasis: Tissue-active amebicide for both intestinal and hepatic amebiasis. First-line for Giardia lamblia infection at 250 mg TID for 5-7 days.
- H. pylori eradication: Triple therapy component (with clarithromycin and PPI) in regions with low clarithromycin resistance.
- C. difficile colitis: First-line oral treatment for mild to moderate CDI at 500 mg TID for 10 days.
Sourcing Metronidazole API: Key Checks
Documentation
Request batch CoA with HPLC purity, 2-methyl-5-nitroimidazole limit, and residual solvent profile. For EU markets, verify CEP status. Ensure the supplier can provide nitrosamine risk assessment per EMA requirements for nitroimidazole APIs.
Red Flags
Elevated 2-methyl-5-nitroimidazole content (incomplete synthesis), dark-colored powder indicating degradation, reluctance to share nitrosamine assessment, and prices well below market average for GMP-grade material.
Packaging & Logistics
Standard: 25 KG/DRUM. Store at controlled room temperature, protected from light (metronidazole is photolabile). Standard lead time 4-8 weeks. Confirm shipping route avoids prolonged high-humidity exposure.
Market Context
Global metronidazole API demand driven by dual human (anaerobic infections, STIs) and veterinary (poultry, swine) markets. China and India are dominant producers. Nitrosamine compliance and environmental regulations on nitroimidazole residues are tightening globally, favoring CE-certified suppliers. Market report